1. Field of the Invention
The present invention relates to an image display apparatus using an image display device represented by liquid crystal panels.
2. Description of Related Art
An image display apparatus using an image display device in which pixels are arranged in a dot-like form and which is represented by a light emitting diode array, a liquid crystal panel of a TFT (thin film transistor) active matrix type etc., has been developed. According to such an image display apparatus the contrast of an image displayed on the image display apparatus is significantly changed by the magnitude of an angle made by a direction for viewing the image display apparatus and a direction orthogonal to a display face of the image display apparatus (that is, an angle whereby a direction in which a viewer is disposed, in view from the display face of the image display apparatus, is deviated from a direction orthogonal to a frontal face of the image display apparatus) and fair image quality can be provided only when the viewer views the image display apparatus right in front thereof or substantially right in front thereof. That is, a viewing angle providing fair image quality is narrow in such an image display apparatus. Accordingly, it is difficult for a number of persons to view one display face of the image display apparatus at the same time. Further, when a large screen of the image display apparatus is viewed in close proximity, there is recognized the difference of contrast between the central portion and the peripheral portion of the display face whereby the image quality is deteriorated.
The above-mentioned problem is particularly significant in an image display apparatus using a liquid crystal panel as an image display device. In order to resolve such a problem a liquid crystal display apparatus (refer to Japanese Unexamined Patent Publication No. 65175/1981) in which a polyhedron lens is arranged on the viewer's side of a liquid crystal panel, a display apparatus (refer to Japanese Unexamined Patent Publication No. 25399/1978) in which a concave lens array is arranged, and the like have been developed. However, sufficient image quality has not been achieved in these conventional image display devices although the viewing angles can be enlarged.